Fats or lipids are other macronutrients necessary for the body. Having many life – saving functions in the body, fats are essential for humans.

Based on the presence or absence of double bonds, fats are classified into saturated and unsaturated groups. The unsaturated fats themselves are categorized into monounsaturated and polyunsaturated groups.

Double bonds based on which fats are classified are sets of carbons that store higher amounts of energy and are chemically very active. Saturated Fat (SF) is a fat that has no double bonds at all.

Monounsaturated Fat (MUSF) is a fat with only one double bond. Polyunsaturated Fat (PUSF) is a fat that has two or more double bonds in its structure.

Food Sources of Different Types of Fats:

Saturated

Monounsaturated

Polyunsaturated

Animal based:

-Beef

-Butter

-Chicken

-Dairy products

-Egg yolk

-Lamb

-Pork

Plant based:

-Coconut oil

-Hydrogenated margarine

-Palm oil

-Vegetable shortenings

Almond oil

Avocado

Canola oil

Cashews

Olive oil

Peanuts

Pecans

Pistachios

Omega – 3:

-Chia seeds

-Fish

-Flaxseeds

-Hemp seeds

-Pumpkin seeds

-Walnut

Omega – 6:

-Black currant oil

-Borage oil

-Corn oil

-Evening primrose oil

-Grapeseed oil

-Poppyseed oil

-Safflower oil

-Sesame oil

-Soybean oil

-Sunflower oil

-Walnut oil

-Wheat germ oil

Most oils and food items contain a combination of all three types of fats with different percentages (see the table below).

Percentage of Different Fats in Different Oils and Food Items:

Oils or Food Items

Saturated Fat

Monounsaturated Fat

Polyunsaturated Fat

Almond butter

10

60

30

Avocado oil

10

75

15

Butter

65

30

5

Canola oil

5

60

35

Coconut oil

93

5

2

Corn oil

15

25

60

Cottonseed oil

25

20

55

Lard

40

50

10

Olive oil

15

75

10

Palm oil

50

40

10

Peanut oil

15

50

35

Pistachio oil

15

55

30

Safflower oil

10

10

80

Soybean oil

15

25

60

Sunflower oil

10

20

70

Tallow

54

45

1

How Much Fat Do We Need?

According to health authorities, the total daily intake of fats in an average person should be about 25% of total daily calories or 65 grams a day, whichever counts lower. For a better understanding, just take a look at the following examples:

Example 1:

Suppose your totally daily calories are 3000. Twenty five percent of your calories would be 750. Since 1 gram of fat generates 9 calories, 750 divided by 9 equals to 83. Your total daily fat intake should be 65 grams, because 65 is smaller than 83.

Example 2:

If your total daily calories are 1800, twenty five percent of it would be 450, which is equal to 50 grams of fat. Your total daily fat intake should be 50 grams, because 50 is smaller than 65.

Daily Needs of Fats:

Fat

Daily intake

Total fat

65 grams

Total saturated fat

20 grams

Cholesterol

300 milligrams

Functions of Fats in the Body (Why Do We Need Fats?):

Fats have many life supporting functions in the body:

1) They are a big part of cell membrane, keeping the cell stronger against invasion by microorganisms and damage by chemicals.

2) They have a key role in the nervous system.

3) They are important in the formation of sex hormones.

4) They play a crucial role in forming bile acids and vitamin D.

5) They are potential sources of energy by generating 9 calories per one gram.

6) They act as a protective blanket, shielding the internal organs from trauma and cold, especially the heart, kidneys, liver, spleen, and spinal cord. About 4% of the body`s fat is in the protective blanket.

7) Fat under the skin helps prevent from heat loss and protect the body against external temperature changes. In fact, the subcutaneous fat helps people tolerate extreme cold by acting a thermal insulation.

8) Fats facilitate absorption of vitamins A, D, E, and K.

9) Lipids are good hunger suppressors. After ingesting fats, it takes about 3 to 4 hours for the stomach to deliver them to the small intestine. In facts, lipids stay longer in the stomach, decreasing the release of hunger hormone, ghrelin, followed by a decrease in hunger feeling.

Cholesterol:

Cholesterol is the main sterol synthesized by the body. The total body content of cholesterol in an average person is about 35 grams, which is primarily incorporated in the cell membranes and a small amount is in the blood. The liver synthesizes approximately 70% of the body`s total cholesterol. Daily production of cholesterol in the body varies between 0.5 and 2 grams.

Triglyceride (TG) constitutes approximately 95% of the fats in the body and foods. It is the stored form of fat and made of glycerol attached to three fatty acids. Glycerol is water – soluble and short chain carbohydrate.

When unsaturated fats are exposed to heat, oxygen and light, they convert to hydroperoxides which break down into volatile aldehydes, esters, alcohols, ketones, and hydrocarbons, giving unpleasant odour and flavour to foods. This chemical process is called “lipid peroxidation” or commonly known as “rancidity”.

In order to prevent from rancidity, antioxidants such as vitamin E, B- carotene, BHT or BHA are usually added to unsaturated fats.

Trans – Fats:

Trans - fats are unsaturated fats in which double bonds have moved from cis-positions to the opposite side to trans-positions. Saturated fats never change to Trans – fats, because they do not contain any double bonds.Tran -fats are made by adding hydrogen to vegetable oils through a process called hydrogenation, which makes the oils less likely to spoil.

Using Trans - fats in manufacturing foods helps foods stay fresh longer, have a longer shelf life and have a less greasy taste.